fn main() {
    let s = {
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).unwrap();
        line.trim().parse::<String>().unwrap()
    };
    let t = {
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).unwrap();
        line.trim().parse::<String>().unwrap()
    };
    let n = {
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).unwrap();
        line.trim().parse::<usize>().unwrap()
    };

    print!("{}", s);
    for _ in 0..n {
        print!("_{}", t);
    }
    println!();
}